1/*
2 *  Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
3 *
4 *  This program is free software; you can redistribute it and/or modify
5 *  it under the terms of the GNU General Public License as published by
6 *  the Free Software Foundation; either version 2 of the License, or
7 *  (at your option) any later version.
8 *
9 *  This program is distributed in the hope that it will be useful,
10 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
11 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 *  GNU General Public License for more details.
13 *
14 *  You should have received a copy of the GNU General Public License
15 *  along with this program; if not, write to the Free Software
16 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17 */
18#ifndef _DCCP_CCID2_H_
19#define _DCCP_CCID2_H_
20
21#include <linux/timer.h>
22#include <linux/types.h>
23#include "../ccid.h"
24#include "../dccp.h"
25
26/*
27 * CCID-2 timestamping faces the same issues as TCP timestamping.
28 * Hence we reuse/share as much of the code as possible.
29 */
30#define ccid2_time_stamp	tcp_time_stamp
31
32/* NUMDUPACK parameter from RFC 4341, p. 6 */
33#define NUMDUPACK	3
34
35struct ccid2_seq {
36	u64			ccid2s_seq;
37	u32			ccid2s_sent;
38	int			ccid2s_acked;
39	struct ccid2_seq	*ccid2s_prev;
40	struct ccid2_seq	*ccid2s_next;
41};
42
43#define CCID2_SEQBUF_LEN 1024
44#define CCID2_SEQBUF_MAX 128
45
46/*
47 * Multiple of congestion window to keep the sequence window at
48 * (RFC 4340 7.5.2)
49 */
50#define CCID2_WIN_CHANGE_FACTOR 5
51
52/**
53 * struct ccid2_hc_tx_sock - CCID2 TX half connection
54 * @tx_{cwnd,ssthresh,pipe}: as per RFC 4341, section 5
55 * @tx_packets_acked:	     Ack counter for deriving cwnd growth (RFC 3465)
56 * @tx_srtt:		     smoothed RTT estimate, scaled by 2^3
57 * @tx_mdev:		     smoothed RTT variation, scaled by 2^2
58 * @tx_mdev_max:	     maximum of @mdev during one flight
59 * @tx_rttvar:		     moving average/maximum of @mdev_max
60 * @tx_rto:		     RTO value deriving from SRTT and RTTVAR (RFC 2988)
61 * @tx_rtt_seq:		     to decay RTTVAR at most once per flight
62 * @tx_cwnd_used:	     actually used cwnd, W_used of RFC 2861
63 * @tx_expected_wnd:	     moving average of @tx_cwnd_used
64 * @tx_cwnd_stamp:	     to track idle periods in CWV
65 * @tx_lsndtime:	     last time (in jiffies) a data packet was sent
66 * @tx_rpseq:		     last consecutive seqno
67 * @tx_rpdupack:	     dupacks since rpseq
68 * @tx_av_chunks:	     list of Ack Vectors received on current skb
69 */
70struct ccid2_hc_tx_sock {
71	u32			tx_cwnd;
72	u32			tx_ssthresh;
73	u32			tx_pipe;
74	u32			tx_packets_acked;
75	struct ccid2_seq	*tx_seqbuf[CCID2_SEQBUF_MAX];
76	int			tx_seqbufc;
77	struct ccid2_seq	*tx_seqh;
78	struct ccid2_seq	*tx_seqt;
79
80	/* RTT measurement: variables/principles are the same as in TCP */
81	u32			tx_srtt,
82				tx_mdev,
83				tx_mdev_max,
84				tx_rttvar,
85				tx_rto;
86	u64			tx_rtt_seq:48;
87	struct timer_list	tx_rtotimer;
88
89	/* Congestion Window validation (optional, RFC 2861) */
90	u32			tx_cwnd_used,
91				tx_expected_wnd,
92				tx_cwnd_stamp,
93				tx_lsndtime;
94
95	u64			tx_rpseq;
96	int			tx_rpdupack;
97	u32			tx_last_cong;
98	u64			tx_high_ack;
99	struct list_head	tx_av_chunks;
100};
101
102static inline bool ccid2_cwnd_network_limited(struct ccid2_hc_tx_sock *hc)
103{
104	return hc->tx_pipe >= hc->tx_cwnd;
105}
106
107/*
108 * Convert RFC 3390 larger initial window into an equivalent number of packets.
109 * This is based on the numbers specified in RFC 5681, 3.1.
110 */
111static inline u32 rfc3390_bytes_to_packets(const u32 smss)
112{
113	return smss <= 1095 ? 4 : (smss > 2190 ? 2 : 3);
114}
115
116/**
117 * struct ccid2_hc_rx_sock  -  Receiving end of CCID-2 half-connection
118 * @rx_num_data_pkts: number of data packets received since last feedback
119 */
120struct ccid2_hc_rx_sock {
121	u32	rx_num_data_pkts;
122};
123
124static inline struct ccid2_hc_tx_sock *ccid2_hc_tx_sk(const struct sock *sk)
125{
126	return ccid_priv(dccp_sk(sk)->dccps_hc_tx_ccid);
127}
128
129static inline struct ccid2_hc_rx_sock *ccid2_hc_rx_sk(const struct sock *sk)
130{
131	return ccid_priv(dccp_sk(sk)->dccps_hc_rx_ccid);
132}
133#endif /* _DCCP_CCID2_H_ */
134